Jeff McLane and Zach Berman

Lane Johnson will miss the first four games of the season after the NFL officially announced Wednesday that the Eagles tackle violated the league's policy on performance-enhancing substances.

Johnson's failed test was first reported last month, but it was unclear at the time what banned substance he had used or whether he planned to file an appeal. He did appeal but owned up to the violation in a statement released by the Eagles after the NFL's announcement.

"In April, while training, I mistakenly and foolishly put a prescribed medication in my body to help with a medical issue," Johnson said. "I mistakenly failed to clear it with Eagles trainers and check the NFL list of banned substances.

"I am extremely sorry for this mistake, and I will learn from it and be smarter in the future."

Johnson's agent declined to identify the medication.

Johnson will miss games against the Jaguars, Colts, Redskins, and 49ers. He is eligible to return to the active roster Sept. 29. Johnson can participate in training camp and play in preseason games, but he will be barred from the Eagles practice facility once the team trims the roster to 53 in late August.

Johnson also can't have any contact with coaches or team officials during the suspension unless he needs to arrange off-site medical treatment.

"We're very disappointed to learn of his suspension," the Eagles said in a statement. "We have spoken to Lane about the details of the suspension. He understood what he did wrong and took full responsibility. The key for him, however, is to learn from that mistake and move forward with his preparation for the 2014 season."

Selected fourth overall in the 2013 draft, Johnson had a solid rookie season. He started all 16 regular-season games plus the playoff game against the Saints and showed steady improvement.

Veteran Allen Barbre is the likely replacement for Johnson at right tackle. He stepped in for injured left tackle Jason Peters against the Packers last November and performed well.

The Eagles gave Barbre a two-year contract extension in May, not long after they learned Johnson had failed his drug test.